236 research outputs found

    The Rockefeller Foundations International Health Board and the Attempt to Eradicate Yellow Fever

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    Beginning in 1914, the Rockefeller Foundation's International Health Commission (which became the International Health Board in 1916 and the International Health Division in 1927) committed itself to the project of eradicating yellow fever. Its efforts were modeled on the sanitary techniques deployed by US sanitarians in Havana in 1901 and, more importantly, during the construction of the Panama Canal between 1904 and 1914, with mosquito control preeminent among them. William C. Gorgas, who led these campaigns and then came to work for the Rockefeller Foundation, argued for a key center approach to yellow fever eradication that targeted the remaining urban endemic foci of infection, with the assumption that once these seed beds of the disease were eliminated, yellow fever would fade from the planet. But as the IHB conducted campaigns in South America, Central America, and West Africa during the late 1910s and 1920s, they discovered that yellow fever's ecology and epidemiology were more complicated than they had assumed, and that a "key center" approach would not work to eradicate the disease. By the 1930s, and particularly with Fred Soper's discovery of sylvan or jungle yellow fever, the Rockefeller Foundation gave up on their eradicationist dream

    Maximum likelihood analysis of systematic errors in interferometric observations of the cosmic microwave background

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    We investigate the impact of instrumental systematic errors in interferometric measurements of the cosmic microwave background (CMB) temperature and polarization power spectra. We simulate interferometric CMB observations to generate mock visibilities and estimate power spectra using the statistically optimal maximum likelihood technique. We define a quadratic error measure to determine allowable levels of systematic error that do not induce power spectrum errors beyond a given tolerance. As an example, in this study we focus on differential pointing errors. The effects of other systematics can be simulated by this pipeline in a straightforward manner. We find that, in order to accurately recover the underlying B-modes for r=0.01 at 28<l<384, Gaussian-distributed pointing errors must be controlled to 0.7^\circ rms for an interferometer with an antenna configuration similar to QUBIC, in agreement with analytical estimates. Only the statistical uncertainty for 28<l<88 would be changed at ~10% level. With the same instrumental configuration, we find the pointing errors would slightly bias the 2-\sigma upper limit of the tensor-to-scalar ratio r by ~10%. We also show that the impact of pointing errors on the TB and EB measurements is negligibly small.Comment: 10 pages, 4 figures, accepted for publication in ApJS. Includes improvements in clarity of presentation and Fig.4 added, in response to refere

    A review of sample analysis at mars-evolved gas analysis laboratory analog work supporting the presence of perchlorates and chlorates in gale crater, mars

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    Funding Information: The research reviewed in this paper was funded by the Mars Science Laboratory (MSL) project office. M.-P.Z. acknowledges funding from the Ministerio de Ciencia e Innovacion (ref. PID2019-104205GB-C21). The authors are grateful to the engineers and scientists of the MSL Curiosity team, who have made the mission possible and the reported data available. The authors would also like to thank the two anonymous reviewers who provided careful reviews that increased the quality of this manuscript. The authors would like to remember and recognize the contributions of Rafael Navarro-Gonzalez, a dedicated SAM and HABIT team member who passed away on 28 January 2021. Navarro-Gonzalez, who was a distinguished researcher, conducted laboratory experiments that demonstrated that chloromethanes could form through a reaction between perchlorates and organics during sample heating, which greatly advanced our understanding of perchlorates and organic detection on Mars. Data Availability Statement: SAM data are publicly available through the NASA Planetary Data System at: http://pds-geosciences.wustl.edu/missions/msl/sam.htm, which was updated in March 2021. See references for the original research articles that contain the data reviewed in this paper.Peer reviewedPublisher PD

    Haloes gone MAD: The Halo-Finder Comparison Project

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    [abridged] We present a detailed comparison of fundamental dark matter halo properties retrieved by a substantial number of different halo finders. These codes span a wide range of techniques including friends-of-friends (FOF), spherical-overdensity (SO) and phase-space based algorithms. We further introduce a robust (and publicly available) suite of test scenarios that allows halo finder developers to compare the performance of their codes against those presented here. This set includes mock haloes containing various levels and distributions of substructure at a range of resolutions as well as a cosmological simulation of the large-scale structure of the universe. All the halo finding codes tested could successfully recover the spatial location of our mock haloes. They further returned lists of particles (potentially) belonging to the object that led to coinciding values for the maximum of the circular velocity profile and the radius where it is reached. All the finders based in configuration space struggled to recover substructure that was located close to the centre of the host halo and the radial dependence of the mass recovered varies from finder to finder. Those finders based in phase space could resolve central substructure although they found difficulties in accurately recovering its properties. Via a resolution study we found that most of the finders could not reliably recover substructure containing fewer than 30-40 particles. However, also here the phase space finders excelled by resolving substructure down to 10-20 particles. By comparing the halo finders using a high resolution cosmological volume we found that they agree remarkably well on fundamental properties of astrophysical significance (e.g. mass, position, velocity, and peak of the rotation curve).Comment: 27 interesting pages, 20 beautiful figures, and 4 informative tables accepted for publication in MNRAS. The high-resolution version of the paper as well as all the test cases and analysis can be found at the web site http://popia.ft.uam.es/HaloesGoingMA

    Perturbative calculation of the scaled factorial moments in second-order quark-hadron phase transition within the Ginzburg-Landau description

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    The scaled factorial moments FqF_q are studied for a second-order quark-hadron phase transition within the Ginzburg-Landau description. The role played by the ground state of the system under low temperature is emphasized. After a local shift of the order parameter the fluctuations are around the ground state, and a perturbative calculation for FqF_q can be carried out. Power scaling between FqF_q's is shown, and a universal scaling exponent Μ≃1.75\nu\simeq 1.75 is given for the case with weak correlations and weak self-interactions.Comment: 12 pages in RevTeX, 12 eps figure

    Antibiotics for coughing in general practice: a questionnaire study to quantify and condense the reasons for prescribing

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    BACKGROUND: Antibiotics are being overprescribed in ambulant care, especially for respiratory tract infections (RTIs). Gaining insight into the actual reasons for prescribing remains important for the design of effective strategies to optimise antibiotic prescribing. We aimed to determine items of importance for the antibiotic prescribing decision and to make them operational for an intervention trial. METHODS: A postal questionnaire based upon focus group findings was sent to 316 Flemish general practitioners (GPs). On a verbal rating scale the GPs scored to what extent they consider the questionnaire items in decision making in case of suspected RTI in a coughing patient and how strongly the items support or counter antibiotic treatment. Factor analysis was used to condense the data. The relative importance of the yielded operational factors was assessed using Wilcoxon Matched Pairs test. RESULTS: 59.5% completed the study. Response group characteristics (mean age: 42.8 years; 65.9% men) approximated that of all Flemish GPs. Participants considered all the items included in the questionnaire: always the operational factor 'lung auscultation', often 'whether or not there is something unusual happening' – both medical reasons – and to a lesser extent 'non-medical reasons' (P < 0.001). Non-medical as well as medical reasons support antibiotic treatment, but non-medical reasons to a lesser extent (P < 0.001). CONCLUSION: This study quantified, condensed and confirmed the findings of previous focus group research. Practice guidelines and interventions to optimise antibiotic prescribing have to take non-medical reasons into account

    Estimating the Extent of Vaccine-Derived Poliovirus Infection

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    BACKGROUND: Eight outbreaks of paralytic polio attributable to circulating vaccine-derived poliovirus (cVDPV) have highlighted the risks associated with oral poliovirus vaccine (OPV) use in areas of low vaccination coverage and poor hygiene. As the Polio Eradication Initiative enters its final stages, it is important to consider the extent to which these viruses spread under different conditions, so that appropriate strategies can be devised to prevent or respond to future cVDPV outbreaks. METHODS AND FINDINGS: This paper examines epidemiological (temporal, geographic, age, vaccine history, social group, ascertainment), and virological (type, genetic diversity, virulence) parameters in order to infer the numbers of individuals likely to have been infected in each of these cVDPV outbreaks, and in association with single acute flaccid paralysis (AFP) cases attributable to VDPVs. Although only 114 virologically-confirmed paralytic cases were identified in the eight cVDPV outbreaks, it is likely that a minimum of hundreds of thousands, and more likely several million individuals were infected during these events, and that many thousands more have been infected by VDPV lineages within outbreaks which have escaped detection. CONCLUSIONS: Our estimates of the extent of cVDPV circulation suggest widespread transmission in some countries, as might be expected from endemic wild poliovirus transmission in these same settings. These methods for inferring extent of infection will be useful in the context of identifying future surveillance needs, planning for OPV cessation and preparing outbreak response plans

    Haloes gone MAD: The Halo-Finder Comparison Project

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    We present a detailed comparison of fundamental dark matter halo properties retrieved by a substantial number of different halo finders. These codes span a wide range of techniques including friends-of-friends, spherical-overdensity and phase-space-based algorithms. We further introduce a robust (and publicly available) suite of test scenarios that allow halo finder developers to compare the performance of their codes against those presented here. This set includes mock haloes containing various levels and distributions of substructure at a range of resolutions as well as a cosmological simulation of the large-scale structure of the universe. All the halo-finding codes tested could successfully recover the spatial location of our mock haloes. They further returned lists of particles (potentially) belonging to the object that led to coinciding values for the maximum of the circular velocity profile and the radius where it is reached. All the finders based in configuration space struggled to recover substructure that was located close to the centre of the host halo, and the radial dependence of the mass recovered varies from finder to finder. Those finders based in phase space could resolve central substructure although they found difficulties in accurately recovering its properties. Through a resolution study we found that most of the finders could not reliably recover substructure containing fewer than 30-40 particles. However, also here the phase-space finders excelled by resolving substructure down to 10-20 particles. By comparing the halo finders using a high-resolution cosmological volume, we found that they agree remarkably well on fundamental properties of astrophysical significance (e.g. mass, position, velocity and peak of the rotation curve). We further suggest to utilize the peak of the rotation curve, vmax, as a proxy for mass, given the arbitrariness in defining a proper halo edg
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